DOI: 10.1051/apido:2004037 Original article

Abstract – The effects of oxalic (OA) and formic acids (FA) on honeybee larvae in colonies were assessed and evaluated. Cell death was detected by the TUNEL technique for DNA labelling. In 3- and 5-day-old larvae exposed to OA, cell death was found in 25 % of midgut epithelial cells 5 h after the treatment, using an “In situ cell death detection kit, AP ” (Roche). The level of cell death increased to 70 % by the 21st hour and the morphology of the epithelium remained unchanged. Fifty hours after the application, cell death was established in 18 % of the epithelial cells of the 3-day-old larvae and had increased to 82 % in the 5-day-old larvae. A “DeadEnd ” apoptosis detection kit (Promega) showed sporadic cell death mainly in the larval fat body 5 h after treatment. Twenty-one hours after the OA application cell death was found in 4 % of the larval midgut epithelial cells. Evaporated formic acid induced extensive apoptotic cell death in the peripheral, cuticular and subcuticular tissues that preceded the cell death of the entire larval body